CA2475289A1 - White-light emitting device, and phosphor and method of its manufacture - Google Patents
White-light emitting device, and phosphor and method of its manufacture Download PDFInfo
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- CA2475289A1 CA2475289A1 CA002475289A CA2475289A CA2475289A1 CA 2475289 A1 CA2475289 A1 CA 2475289A1 CA 002475289 A CA002475289 A CA 002475289A CA 2475289 A CA2475289 A CA 2475289A CA 2475289 A1 CA2475289 A1 CA 2475289A1
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- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims abstract description 134
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000000034 method Methods 0.000 title claims description 18
- 239000012190 activator Substances 0.000 claims abstract description 46
- 229910052802 copper Inorganic materials 0.000 claims abstract description 28
- 229910052737 gold Inorganic materials 0.000 claims abstract description 23
- 229910052709 silver Inorganic materials 0.000 claims abstract description 11
- 229910052740 iodine Inorganic materials 0.000 claims description 14
- 239000012298 atmosphere Substances 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052794 bromium Inorganic materials 0.000 claims description 5
- 229910052801 chlorine Inorganic materials 0.000 claims description 5
- 230000003081 coactivator Effects 0.000 claims description 5
- 229910052733 gallium Inorganic materials 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 229910052738 indium Inorganic materials 0.000 claims description 5
- 230000001678 irradiating effect Effects 0.000 claims 1
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 20
- 230000005284 excitation Effects 0.000 description 18
- 238000010586 diagram Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 7
- 229920001059 synthetic polymer Polymers 0.000 description 7
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 description 6
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 5
- 238000000295 emission spectrum Methods 0.000 description 5
- 239000011630 iodine Substances 0.000 description 5
- 239000003086 colorant Substances 0.000 description 4
- 238000000695 excitation spectrum Methods 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- QNRATNLHPGXHMA-XZHTYLCXSA-N (r)-(6-ethoxyquinolin-4-yl)-[(2s,4s,5r)-5-ethyl-1-azabicyclo[2.2.2]octan-2-yl]methanol;hydrochloride Chemical compound Cl.C([C@H]([C@H](C1)CC)C2)CN1[C@@H]2[C@H](O)C1=CC=NC2=CC=C(OCC)C=C21 QNRATNLHPGXHMA-XZHTYLCXSA-N 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000002189 fluorescence spectrum Methods 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 244000241463 Cullen corylifolium Species 0.000 description 1
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000135 prohibitive effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
- H01L33/50—Wavelength conversion elements
- H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
- H01L33/502—Wavelength conversion materials
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/88—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing selenium, tellurium or unspecified chalcogen elements
- C09K11/881—Chalcogenides
- C09K11/883—Chalcogenides with zinc or cadmium
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
- C30B29/48—AIIBVI compounds wherein A is Zn, Cd or Hg, and B is S, Se or Te
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
- H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
- H01L2224/45001—Core members of the connector
- H01L2224/45099—Material
- H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
- H01L2224/45138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
- H01L2224/45144—Gold (Au) as principal constituent
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
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- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/4805—Shape
- H01L2224/4809—Loop shape
- H01L2224/48091—Arched
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- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/481—Disposition
- H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
- H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
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- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/481—Disposition
- H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
- H01L2224/48257—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a die pad of the item
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- H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
- H01L2924/161—Cap
- H01L2924/1615—Shape
- H01L2924/16195—Flat cap [not enclosing an internal cavity]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract
White-light emitting device that excels in emission efficiency and temperature stability and that can put out white light of a color temperature of choice is afforded by utilizing phosphors of superior temperature characteristics and high light-emitting efficiency; the phosphors and a method of manufacturing the phosphors are also made available. An LED (1), and a phosphor (3) ZnS x Se1-x(0 < x < 1) that contains at least one activator among Cu, Ag and Au and that, excited by light irradiated from the LED, produces light are furnished.
Description
WHITE-LIGHT EMITTING DEVICE, AND PHOSPHOR AND
METHOD OF ITS MANUFACTURE .
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to white-light emitting devices, phosphors utilized in the devices, and to methods of manufacturing the phosphors.
Description of the Background Art Reference is made to Fig. 11, a view depicting an example of a conventional white-light emitting device. (See for example Optically Active Materials Manual Managing Editorial Group, Eds., "OpticallyActive Materials Manual," The Optronics Co., Ltd., June 1997.) In Fig. 11, surrounding an InGaAs blue LED 101 disposed in the mounting portion 109 of a lead frame is an encompassing synthetic-polymer casting 106 in which a YAG
(yttrium-aluminum-garnet) phosphor is dispersed. A molded synthetic-polymer seal 116 seals the casting 106, metal wires 105, and the lead frame. Through the wires 105 out of separated respective portions of the lead frame, voltage is applied across two electrodes 10'7a and 10'7b, and current flows into the blue LED 101 to give rise to a blue-light emission. A portion of the blue light is used to excite the YAG phosphor and generate yellow light, and by combining the yellow light and the blue light, white light is realized. Herein, a YAG
phosphor activated with cerium is employed. Employing light o~f 460 nm as the blue light, with the spectrum of the converted yellow light centering on about 570 nm, a device that emits white light at a color temperature on the order of 7000 K is realized.
Meanwhile, a method of producing white light by converting a portion of blue light from, as represented in Fig. 12, a blue LED 101 of the ZnCdSe type in which a ZnSe substrate 110 is employed, into yellow light by means of the ZnSe substrate, which contains fluorescing impurities or defects, has been proposed.
(See Japanese Unexamined Pat. App. Pub. No. 2000-150961.) This method employs blue light of 485 nm and yellow light whose spectrum centers on 585 nm to realize white light at a color temperature of choice from 10,000 K to 2,500 K. In addition, as a cross between these two methods, a method of producing white light by converting a portion of blue light from an InGaN blue LED into yellow light using a ZnSe phosphor has also been proposed. (See Japanese Unexamined Pat. App. Pub. No. 2000-261034.) If the synthesis of colors in the conventional white-light emitting devices described above is examined in a chromaticity diagram as in Fig. 13, with the ZnSe white-light emitting device, the locus for white light, and the tie line joining the LED blue light and substrate emission roughly coincide. Therefore, simply by varying the proportions of blue light and yellow light, white light of a color temperature of choice can be produced. Nevertheless, a drawback with ZnSe LEDs is that they have a short lifespan because they are prone to deterioration.
With InGaN white-light emitting devices on the other hand, as will be understood from Fig. 13, the tie line joining the blue light and yellow light is at an incline with respect to the locus for white. This means that white Light of a color temperature of choice cannot be synthesized, and in particular is prohibitive of synthesizing white light of color temperature lower than the proximity of 5000 K. In general, because the color temperature of white electric-light bulbs is a low 3500 K or thereabouts, with InGaN white-light emitting devices white light of the same color temperature as with white light bulbs cannot be realized and only white light of color temperature differing from that of white light bulbs is feasible. Consequently, white light bulb replacements by means of InGaN white-light emitting devices, despite having superior lifespan and efficiency characteristics, have not made sufficient progress.
In the case of the method by which white light; is produced by converting a portion of the blue light from an InGaN blue LED into yellow light by means of, for example, a ZnSe phosphor, employing a blue LED whose emission wavelength is in the proximity of 485 nm resolves the foregoing problem. As will be demonstrated in detail later, however, as a phosphor the conversion efficiency of ZnSe is not high and its temperature characteristics are not satisfactory. Consequently, superior white-light sources are not practicable in cases in which ZnSe is utilized.
The white LEDs in any of the foregoing cases synthesize white by mixing together blue light and yellow or yellow-green light. Nevertheless, because green light and red light are deficient in these cases, one would be hard-pressed to suggest that the LEDs would be an ideal illuminant as a backlight for color liquid crystal displays or a light source in lighting applications. Given the circumstances, with the aim of achieving white LEDs in which three primary colors, red-green-blue, are blended, at present the development of methods that employ ultraviolet-light-emitting LEDs to blend fluorescence of three kinds is intensively underway. One roadblock, however, is that because the emission efficiency of ultraviolet LEDs is lower than the efficiency of blue light LEDs the efficiency with which white light is emitted ends up being as a consequence low.
SUMMARY OF THE INVENTION
An object of the present invention is by utilizing phosphors of superiox temperature characteristics and high Iight-emitting efficiency to afford a white-Iight emitting device that excels in emission efficiency and temperature stability and that can produce white light of a color 1=emperature of choice, and I5 to make available the phosphors and a method of manufacturing the phosphors.
A white-Iight emitting device in one aspect of the present invention is furnished with: an LED and a phosphor ZnSXSe1_X (0 < x < I) that contains at least one activating agent (activator) among Cu, Ag and Au and that, stimulated by rays irradiated from the LED, sends forth Iight.
This configuration provides for constructing a white-light emitting device whose temperature characteristics are stable and that utilizes a phosphor of high emission efficiency, which thus allows high-efficiency white-light emitting devices whose hue does not alter from long-term use to be achieved.
The abovementioned phosphox may be ZnS,YSe1_x (0_2 <_ x <_ 0.9), and may be rendered so that, stimulated by rays in a range of wavelengths 380 nm to nm irradiated from the LED, the phosphor sends forth light.
By combining a blue LED and a phosphor that produces fluorescence of 5 wavelength longer than that from the LED, this configuration enables a white-light emitting device of stabilized hue to be achieved.
The foregoing phosphor ZnSxSel X (0 < x < 1) further may contain at least one coactivator among Cl, Br, I, Al, In and Ga.
Utilizing the coactivator allows the light-emission efficiency to be heightened further.
The foregoing phosphor ZnSxSel X (0 < x < 1) may be in either a clumplike or powdered form.
Although phosphor usage methods that incorporate it as a powder into a synthetic polymer are well-known ways of employing the material, if it is in clump form, temperature elevation can be kept under control since heat generated within the phosphor is readily given off to the exterior.
A foregoing phosphor ZnSXSe~ X (0.5 < x S 0.9) may contain at least one of the activators Au and Cu, and be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from the LED, the phosphor sends forth light.
The configuration just noted, given that at least one of Au and Cu is employed for the activator, viewed in terms of efficiency enables the optimal combination of the two fluorescers that are components of the white-light emitting device to be achieved.
An aforementioned phosphor ZnS,YSe1 x (0.4 5 x 5 0.5) may contain the activator Ag and, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from the LED, sends forth light.
This configuration, viewed in terms of efficiency given that Ag is employed for the activator, enables an optimal combination constituting the white-light emitting device to be formed.
A white-light emitting device in another aspect of the invention may include, as the phosphor ZnSxSel X (0 < x < 1), at least one of a phosphor ZnSxSe1 X (0.7 <_ xS 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSei X (0.5 <_ x <_ 0.8) containing the activator Ag, and may be furnished with an LED that irradiates light in a range of wavelengths 410 nm to 490 nm, and a separate LED that irradiates red light.
According to this configuration, an RGB white-light emitting device can be constituted with the green (G) role being taken on by either of the phosphors just noted, and with a blue LED and a red LED. With red light therefore also being included, white light that for all applications is trouble-free can be made available.
A white-light emitting device in a further aspect of the present invention may include as the phosphor ZnSxSe1-X (0 < x < 1), at least one of a phosphor ZnSXSe1_X (0.7 < x< 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSe1 x (0.5 < x < 0.8) containing the activator Ag, and be additionally furnished with a separate phosphor that sends forth light of wavelength longer than that from the phosphor just noted, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors senf, forth light.
According to this configuration, with the green light (G) and red light (R) roles being taken on by phosphors of two kinds, and brought together with blue Light (B) from a blue LED, white light utilizable in all applications, including as a backlight for a liquid-crystal display, can be created.
A white-light emitting device in yet another aspect may include as the phosphor ZnSXSei-X (0 < x< 1), at least one of a phosphor ZnSXSe~_X (0.7 <_ x<_ 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSe1 X
(0.5 < x _< 0.8) containing the activator Ag, and additionally be furnished with, as a separate phosphor, ZnSxSe1-x (0.2 <_ x_< 0.4) containing at least one of the activators Au and Cu, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors send forth light.
According to this configuration, the rel-light and green-Iight roles are taken on by ZnSSe phosphors and are brought together with blue light from a blue LED, wherein an RGB type of white-light emitting device applicable to any use whatever can be formed.
In an additional aspect of the present invention a white-light emitting device may be furnished with, as the phosphor ZnSxSe 1 x (0 < x < 1), a phosphor ZnSXSe1-X (0.2 < x_< 0.4) containing at Least one of the activators Au and Cu, and also be furnished with a separate phosphor that sends forth green light, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors send forth light.
This configuration brings together red-light whose role is taken on by the phosphor ZnSxSe 1 X (0.2 5 x <_ 0.4) and green Light that is allotted to another suitable phosphor with blue light from a blue LED to enable an RGB white-light emitting device to be formed.
The phosphor ZnSxSel X (0 < x< 1) may be in clumplike form, and may be mounted on, so as to mate surfaces with, either the blue LED or a heat-dissipating member furnished in the white-light emitting device.
With a clumplike phosphor, heat arising in the interior is readily transmitted to the phosphor surface'> mounting the phosphor as just mentioned on either a heat-dissipating member or the blue LED so that the mounting surfaces mate facilitates letting the heat escape.
An InGaN LED may be utilized for the foregoing blue LED. That makeup provides for a stable, low-cost blue LED, which contributes to achieving a highly reliable white-light emitting device.
It is preferable that the foregoing phosphors ZnSxSei X (0 < x < 1) be heat-treated in an atmosphere containing Zn vapor.
Through a technique of this sort phosphors of high fluorescing efficiency can be achieved.
A phosphor-manufacturing method of the present invention includes: a step of forming a phosphor ZnSxSe1 X (0 < x < 1) containing at least one among coactivators Cl, Br, I, Al, In and Ga~ and a step of carrying out a process, within a vaporous mixture of a vapor of at least one of activators Au, Cu and Ag and a vapor of Zn, of heating the coactivator-containing phosphor ZnSx,Se1_X (0 < x < 1) to the vaporous mixture temperature.
This method yields a phosphor ZnSXSe1-X (0 < x< 1) of high light-emission efficiency, containing activators and coactivators.
A white-light emitting device of the present invention, by utilizing fluorescing materials such as phosphors, makes it possible stably to produce, with good efficiency and without altering of hue relative to changes in temperature, white light of a color temperature of choice.
From the following detailed description in conjunction with the accompanying drawings, the foregoing and other objects, features, aspects and advantages of the present invention will become readily apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a chart showing that in embodying the present invention the temperature dependence of ZnSe phosphor is significant Fig. 2 is diagram illustrating basic thinking in the development of the phosphors ZnSxSel X in embodying the present invention Fig. 3 is a diagram showing fluorescence spectra for ZnSSe in which the activator Cu is utilized Fig. 4 is a diagram showing fluorescence spectra far ZnSSe in which the activator Ag is utilized Fig. 5 is a chromaticity diagram plotting the spectral peaks for ZnSSe in which the activator Cu is utilized and in which Ag is~
Fig. 6 is a chart showing the dependence of spectral peak on S atomic fraction, for ZnSSe in which the activator Cu is utilized and in which Ag is~
5 Fig. '7 is a chart illustrating the temperature dependence of the fluorescent intensity of ZnSSe in which the activator Cu is utilized Fig. 8 is a chart illustrating the temperature dependence of the fluorescent intensity of ZnSSe in which the activator Ag is utilized Fig. 9 is a view illustrating the configuration of a white-light emitting 10 device of Embodiment 1 of the present invention Fig. 10 is a view depicting the configuration of a white-light emitting device of Embodiment 2 of the present invention Fig. 11 is a view showing the configuration of a conventional white-light emitting device Fig. 12 is a view representing the configuration of another conventional white-light emitting device and Fig. 13 is a chromaticity diagram plotting color data for conventional white-light emitting devices.
DETAILED DESCRIPTION OF THE INVENTION
Next, using the drawings, an explanation of embodiments of the present invention will be made.
Basic Concept of the In vention In developing phosphors, crucial characteristics are the excitation-emission properties, and the emission efficiency. As far as the excitation-emission properties are concerned, in instances in which blue LEDs, which have seen significant advances in recent years, are employed as an optical excitation source the phosphors must be efficiently stimulated by blue light and exhibit fluorescence in yellow, which is blue's complementary color.
If white LEDs of the RGB type are to be manufactured, then it is necessary for the phosphors to express by blue light red and green fluorescence. The emission efficiency of a phosphor can be evaluated according to the dependence of its fluorescent intensity on temperature. In general, at low temperature phosphors have high emission efficiency, while their fluorescing efficiency drops with elevations in temperature. However, to what extent can the temperature be raised before the efficiency drops differs depending on the kind of phosphor.
Accordingly, if the fluorescence efficiency of a phosphor does not vary from low temperature to the temperature zone in which phosphors are employed, then its temperature characteristics are satisfactory and its emission efficiency is high.
If conventional phosphors are evaluated from these perspectives, then the fact that YAG types are limited to the yellow band means that their excitation-emission properties are inadequate. Zn~'e phosphors demonstrate emission that is convenient in terms of synthesizing white light of a color temperature of choice, but the wavelength of the excitation beam is restricted to 485 nm or thereabouts, and in that wavelength bandL the emission efficiency of an InGaN LED ends up being rather low. Consequently, the combination of wavelengths from YAG and ZnSe phosphors is not necessarily optimal.
Moreover, the temperature behavior of ZnSe phosphor was assayed, which indicated, as shown in Fig. I, that the temperature characteristics of ZnSe phosphor are not necessarily the best. At or around room temperature, ZnSe phosphor already exhibits remarkable temperature quenching, and not only is the efficiency not high, according as the LED temperature changes the proportions of blue and yellow light change, which ends up altering the hue (color temperature, etc.) of the white.
Under the circumstances, then, attention in the present invention was IO given to ZnS phosphors. ZnSe and ZnS are similar phosphors in which only the Se and S are interchanged. With ZnS, on account of its wider band gap than that of ZnSe, excitation light from violet to ultraviolet would be necessary in order to propose ZnS Iuminophors. Consequently, ZnS is not usable in white LEDs of the blue-light-excitation type. Nevertheless, ZnS phosphors have superlative temperature characteristics, and thus are widely used as phosphors for electron-beam excitation such as in television cathode-ray tubes. In light of these considerations, as represented in Fig. 2, the concept was hit upon that a phosphor possessing the combined superior features of ZnSe phosphors and ZnS
phosphors ought to be realizable with ZnS~Se1-X (0 < <~< 1), being a solid solution of ZnSe and ZnS.
It should be understood that while only "Z:nSe phosphors" and "ZnS
phosphors" have been referred to, in order for ZnSe and ZnS to operate as phosphors, it is necessary to disperse activators and coactivators into the paxent material (in this case ZnSe and ZnS). As activators for ZnS
luminophors, the Group Ib elements Ag, Cu and Au are known. Likewise, as coactivators, the Group VIIa elements F, Cl, Br and I, as well as the Group IIIa elements Al, In and Ga are known. As far as coactivators are concerned, the phosphor emission behavior does not change much no matter what element is used.
As far as activators are concerned, it is known that the fluorescent wavelength shortens when Ag is used, and lengthens when Cu or Au is used.
There is no major difference between Cu and Au. Given these considerations, activators and coactivators were introduced into ZnSXSe~ X of a variety of S
atomic fractions (x) to prepare phosphors, and their excitation-emission properties and temperature characteristics were investigated to find out whether they could be exploited in fabricating white LEDs.
Phosphor ,Selection ZnSSe into which iodine was incorporated by the iodine transport method was composed. ZnSSe phosphors were prepared by diffusing Cu or Ag into the ZnSSe within a Zn atmosphere. The results are set forth in the following.
Emission spectra for ZnS,riSe r_x (x = 0, 0.25, 0.4, 0.6, 0.8) into which Cu and I were introduced, and emission spectra for ZnS,YSex x (x = 0, 0_4, 0.6, 0.8) into which Ag and I were introduced are shown respectively in Fig. 3 and Fig.
4.
For the measurements, a beam from a He-Cd laser of 325 nm wavelength was employed as the excitation light. In either instance, with increasing S atomic fraction x the fluorescent wavelength is shortened. As to the activators, it is evident from the spectra that with the ZnSSe phosphors in which Ag was employed, the fluorescent wavelength is shorter than with those in which Cu was employed.
Chromaticities were calculated from the spectra in Figs. 3 and 4 and plotted on the Fig. 5 chromaticity diagram. As will be understood from Fig. 5, these chromaticity coordinates form the complementary colors for violet to blue-green, 380 to 500 nm~ thexefore, blending these phosphor fluorescences with light of 380 to 500 nm can yield white. The problem remaining was whether the ZnSSe phosphor can be stimulated by the abovementioned visible light. Thus, an excitation spectrum for ZnSSe (change in fluorescent intensity as the excitation wavelength is varied) was measured to find the excitation peak. Therein, a ZnSSe phosphor of 1 mm thickness was used in the measurement.
In Fig. 6 the peak wavelengths in the excitation spectrum for ZnSxSer x (x = 0, 0.25, 0.4, 0_6, 0.8) into which Cu and I were introduced, and the peak wavelengths in the excitation spectrum for ZnS~Sea X (x = 0, 0.4, 0.6, 0.8) into which Ag and I were introduced are shown. In either case, when the S atomic fraction is enlarged the peak in the excitation spectrum is shortened in wavelength. Although a measurement was not made on a phosphor in which the S atomic fraction is 1-that is, on ZnS--extrapolating from the data in Fig. 6, it may be inferred that up until the S atomic fraction is about 0.9, the phosphor may be stimulated with visible rather than ultraviolet light.
Next the dependence of fluorescent intensity on temperature was measured. The results are arranged together in Figs. 7 and 8. It is evident from Figs. 7 and 8 that rendering the S atomic fraction x about 0.2 or more dramatically improves the temperature characteristics by comparison to the case in which the S atomic fraction is zero (ZnSe).
5 Illuminating the phosphor with excitation rays of the foregoing violet to blue-green of 380 to 500 nm, and mixing together the fluorescence and the excitation rays allows white and the intermediate colors surrounding it (pink, pale green, bluish white, etc.) to be synthesized. In order to produce the white that is industrially most important, however, the combination of excitation rays 10 and phosphor can be narrowed down a little more.
s1-First, the instances in which Cu and Au were employed as activators are examined. In these cases, if the S atomic fraction x were low, the temperature characteristics would suffer, and further, longer-wavelength excitation rays would be necessary. With InGaN LEDs, because the efficiency 15 with which they excite proves to be highest at wavelengths in the vicinity of 400 to 4v0 nm, they are undesirable to use for longer-wavelength excitation light.
Using ZnS~Se1 X (0.5 <_ x <_ 0.9) for the phosphor and using an LED whose emission spectrum spans wavelengths of 410 to 490 nm for the excitation rays is preferable.
s2 - Next, the instance in which Ag was employed is considered in the same way, wherein using ZnS~Se1_X (0.4 _< x< 0.5) for the phosphor and using an LED whose emission spectrum spans wavelengths of 410 to 460 nm for the excitation rays is preferable.
The foregoing phosphors may also be employed as the green phosphor and red phosphor for a white LED of the RGB type.
G- In cases in which Au or Cu are employed as activators, ZnSx,Se1 ~ (0.7 S x <_ 0.9) may be utilized for the green phosphor. Likewise, in cases employing Ag as an activator, ZnSxSes-x (0.5 < x <_ 0.8) may be utilized. In composing an RGB type of white, ZnSSe phosphors may be used for both the red phosphor and the green phosphor, or for one or the other a different phosphor may equally well be used.
R - In turn, as far as red light is concerned, since high-efficiency red LEDs are available, a red LED may be employed instead of a red phosphor. A
problem in that case, however, is that since the deterioration rates of blue LEDs and red LEDs are different, the hue of the white will end up varying over time.
All told, it would seem that combining slow-to-deteriorate phosphors would be advantageous over blue LEDs as an optical excitation source.
It should be noted that although the activators were dispersed into the foregoing phosphors within a Zn atmosphere, they may equally well be dispersed within for example an Se atmosphere. Nevertheless, empirically there is a likelihood that the fluorescing efficiency of phosphors into which activators have been dispersed within an Se atmosphere will turn out low.
Features of ZnSSe phosphors include, to name examples, the fact that the source materials are modestly priced and that clumplike rather than powdered phosphors can easily be synthesized. Routinely, phosphors have been rendered into powder form, and have been spread onto a glass substrate or have been dispersed into a.synthetic polymer. With ZnSSe phosphors, nevertheless, the phosphors can be employed in clump form without making them into a powder, eliminating cost problems. While that is an advantage to using clumplike phosphors, compared with the situation in which a phosphor is dispersed into a synthetic polymer, with a clumplike phosphor, because heat generated inside the phosphor is readily dissipated to the exterior, the phosphor temperature is not liable to rise. Consequently, the lifespan of the white LEDs is prolonged as a result, enabling high-output-power white LEDs to be realized.
White Light EmittingDevice Configuration Reference is now made to Fig. 9, a view illustrating the configuration of a white-light emitting device in Embodiment 1 of the present invention. A blue LED I is attached to a mounting portion 9 of a lead frame so that their like surfaces are matched. Through wires 5 out of external electrodes 7a, '7b, electric current is conducted into (not-illustrated) chip electrodes on the blue LED 1.
A
heat-dissipating member 11 made of aluminum is disposed encompassing the blue LED. A transparent polymer 6 into which a~ diffusant is dispersed is disposed covering the blue LED, and a phosphor plate 3 is arranged atop the transparent polymer 6.
The phosphor 3 is established from ZnSxSe1 X of S atomic fraction x, and an activator, and is adjusted so as to lead to white light of a predetermined color temperature. Adjusting the composition of and the activator in the phosphor ZnSRSe1 ~ to attain white light of a predetermined color temperature is an important element of the present invention. Furthermore, what with the specific weights for adjustment being small and the breadth of the adjustment being limited, in some cases the emission spectrum of the blue LED is also an object of adjustment.
The blue LED into which current has been fed through the external electrodes 7a, 7b emits Light of a blue color, shining the light onto the phosphor 3. The light irradiated from the blue LED 1 is shone onto the phosphor plate 3, and this fluorescent emission material is stimulated to give off fluorescence.
Though the rays irradiated from the blue LED 3 illuminate the phosphor plate 3, this does not mean that all are utilized in excitation some pass through the phosphor plate 3 without contributing to excitation. Consequently, fluorescence of a predetermined wavelength and blue light emitted from the blue LED are combined to create white light of a predetermined color temperature.
Reference is made to Fig. 10, a view representing a white-light emitting device in Embodiment 2 of the present invention. What is different from the I5 white-Iight emitting device represented in Fig. 9 is that two phosphors are Laid out-a first phosphor 3 and a second phosphor 13. The first phosphor 3 is a green phosphor, and is formed for example by a ZnSSe plate (ZnS atomic fraction 0.6). Likewise, the second phosphor I3 is a red phosphor, and is formed for example by ZnSSe crystal (ZnS atomic fraction: 0.25). An RGB-type of white-light emitting device can be configured by the blue LED 1, and the foregoing red phosphor 13 and green phosphor 3.
Embodiments Embodiment 1 The white-light emitting device depicted in Fig. 9 was prepared. At first a ZnSSe crystal was grown using the iodine transport method and subsequently underwent heat treatment within a 1000°C atmosphere in which Zn and Cu vapors were mixed, whereby a ZnSo.sSeo.4 crystal of predetermined composition (ZnS atomic fraction 0.6) was prepared. This phosphor corresponds to the rhombic mark for ZnS atomic fraction 0.6 nearby wavelength 570 nm on the chromaticity diagram; and is a yellow-light emitting phosphor. A ZnSSe plate of 250 microns thickness was cut out from the ZnSo.sSeo.4 crystal. Both sides of the ZnSSe plate were polished to a mirror-like finish, bringing the thickness down to 200 urn, and the polished plate was sliced into a 3 mm square to produce a ZnSo.sSeo.4 phosphor plate.
In addition, a blue LED chip of 450 nm emission wavelength, having an InGaN active layer, was readied. An Ag paste was employed to bond the LED
chip onto a chip die (lead-frame mounting portion) 9, as shown in Fig. 9, made of Al. Furthermore, the LED-chip electrodes and the chip-die electrodes were wire-bonded with Au wire. Thereafter, by covering the LED with a transparent synthetic polymer 6, and installing the ZnSSe phosphor plate 3 above the LED, a white-light emitting device was fabricated. Current was passed into the white-light emitting device to cause it to emit light, giving rise to blue light issuing from the LED and yellow fluorescence sent forth by excitation via the blue light, whereby emission of white light of 5000 K color temperature could be produced.
Embodiment 2 The white-light emitting device depicted in Fig. 10 was prepared. A
ZnSSe plate of 250 microns thickness was cut out from a ZnSo.sSeo.4 crystal (ZnS
atomic fraction 0.6) at first being grown using the iodine transport method, and subsequently undergoing heat treatment within a 1000°C atmosphere in which 5 Zn and Ag vapors were mixed. This phosphor corresponds to the black-dot mark for ZnS atomic fraction 0.6 on the chromaticity diagram, and is a green-light emitting phosphor. Both sides of the ZnSSe plate were polished to a mirror-like finish, bringing the thickness down to 200 microns, and the polished plate was sliced into a 3 mm square to produce a ZnSSe phosphor plate (green phosphor:
10 first phosphor).
In addition, a 400-micron square, 250-naicron thick ZnSo.2sSeo.~S
phosphor plate (red phosphor: second phosphor) was prepared from a ZnSo.2sSeo.~S crystal (ZnS atomic fraction 0.25) that was grown using the iodine transport method and subsequently underwent heat treatment within a 1000°C
15 atmosphere in which Zn and Cu vapors were mixed. This phosphor corresponds to the rhombic mark for ZnS atomic fraction 0.25 on the chromaticity diagram and is a red-light emitting phosphor.
In addition, a blue LED chip of 450 nm emission wavelength, having an InGaN active layer, was readied. An Ag paste was employed to bond the LED
20 chip onto the chip die (mounting portion of a lead frame) 9, as shown in Fig. 10, made of Al, and further the LED-chip electrodes and the chip-die electrodes were wire-bonded with Au wire. In addition, the second phosphor was also bonded to the chip die.
Thereafter, by covering the LED with a transparent synthetic polymer 6 into which a diffusant was dispersed, and then inst;~lling the ZnSSe phosphor plate as the first phosphor 3 above the LED, an RGB type of white-light emitting device was fabricated. By passing current into the white-light emitting device to cause it to emit light, emission of white light of 5000 K color temperature could be produced.
A white-light emitting device of the present invention, by utilizing fluorescing materials such as phosphors, makes it possible stably to produce, with good efficiency and without altering of hue relative to changes in temperature, white light of a color temperature of choice, and therefore is expected to find wide-ranging uses in commercial applications and industrial applications in which great importance is attached to hue.
Only selected embodiments have been chosen to illustrate the present invention. To those skilled in the art, however, it will be apparent from the foregoing disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing description of the embodiments according to the present invention is provided for illustration only, and not for limiting the invention as defined by the appended claims and their equivalents.
METHOD OF ITS MANUFACTURE .
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to white-light emitting devices, phosphors utilized in the devices, and to methods of manufacturing the phosphors.
Description of the Background Art Reference is made to Fig. 11, a view depicting an example of a conventional white-light emitting device. (See for example Optically Active Materials Manual Managing Editorial Group, Eds., "OpticallyActive Materials Manual," The Optronics Co., Ltd., June 1997.) In Fig. 11, surrounding an InGaAs blue LED 101 disposed in the mounting portion 109 of a lead frame is an encompassing synthetic-polymer casting 106 in which a YAG
(yttrium-aluminum-garnet) phosphor is dispersed. A molded synthetic-polymer seal 116 seals the casting 106, metal wires 105, and the lead frame. Through the wires 105 out of separated respective portions of the lead frame, voltage is applied across two electrodes 10'7a and 10'7b, and current flows into the blue LED 101 to give rise to a blue-light emission. A portion of the blue light is used to excite the YAG phosphor and generate yellow light, and by combining the yellow light and the blue light, white light is realized. Herein, a YAG
phosphor activated with cerium is employed. Employing light o~f 460 nm as the blue light, with the spectrum of the converted yellow light centering on about 570 nm, a device that emits white light at a color temperature on the order of 7000 K is realized.
Meanwhile, a method of producing white light by converting a portion of blue light from, as represented in Fig. 12, a blue LED 101 of the ZnCdSe type in which a ZnSe substrate 110 is employed, into yellow light by means of the ZnSe substrate, which contains fluorescing impurities or defects, has been proposed.
(See Japanese Unexamined Pat. App. Pub. No. 2000-150961.) This method employs blue light of 485 nm and yellow light whose spectrum centers on 585 nm to realize white light at a color temperature of choice from 10,000 K to 2,500 K. In addition, as a cross between these two methods, a method of producing white light by converting a portion of blue light from an InGaN blue LED into yellow light using a ZnSe phosphor has also been proposed. (See Japanese Unexamined Pat. App. Pub. No. 2000-261034.) If the synthesis of colors in the conventional white-light emitting devices described above is examined in a chromaticity diagram as in Fig. 13, with the ZnSe white-light emitting device, the locus for white light, and the tie line joining the LED blue light and substrate emission roughly coincide. Therefore, simply by varying the proportions of blue light and yellow light, white light of a color temperature of choice can be produced. Nevertheless, a drawback with ZnSe LEDs is that they have a short lifespan because they are prone to deterioration.
With InGaN white-light emitting devices on the other hand, as will be understood from Fig. 13, the tie line joining the blue light and yellow light is at an incline with respect to the locus for white. This means that white Light of a color temperature of choice cannot be synthesized, and in particular is prohibitive of synthesizing white light of color temperature lower than the proximity of 5000 K. In general, because the color temperature of white electric-light bulbs is a low 3500 K or thereabouts, with InGaN white-light emitting devices white light of the same color temperature as with white light bulbs cannot be realized and only white light of color temperature differing from that of white light bulbs is feasible. Consequently, white light bulb replacements by means of InGaN white-light emitting devices, despite having superior lifespan and efficiency characteristics, have not made sufficient progress.
In the case of the method by which white light; is produced by converting a portion of the blue light from an InGaN blue LED into yellow light by means of, for example, a ZnSe phosphor, employing a blue LED whose emission wavelength is in the proximity of 485 nm resolves the foregoing problem. As will be demonstrated in detail later, however, as a phosphor the conversion efficiency of ZnSe is not high and its temperature characteristics are not satisfactory. Consequently, superior white-light sources are not practicable in cases in which ZnSe is utilized.
The white LEDs in any of the foregoing cases synthesize white by mixing together blue light and yellow or yellow-green light. Nevertheless, because green light and red light are deficient in these cases, one would be hard-pressed to suggest that the LEDs would be an ideal illuminant as a backlight for color liquid crystal displays or a light source in lighting applications. Given the circumstances, with the aim of achieving white LEDs in which three primary colors, red-green-blue, are blended, at present the development of methods that employ ultraviolet-light-emitting LEDs to blend fluorescence of three kinds is intensively underway. One roadblock, however, is that because the emission efficiency of ultraviolet LEDs is lower than the efficiency of blue light LEDs the efficiency with which white light is emitted ends up being as a consequence low.
SUMMARY OF THE INVENTION
An object of the present invention is by utilizing phosphors of superiox temperature characteristics and high Iight-emitting efficiency to afford a white-Iight emitting device that excels in emission efficiency and temperature stability and that can produce white light of a color 1=emperature of choice, and I5 to make available the phosphors and a method of manufacturing the phosphors.
A white-Iight emitting device in one aspect of the present invention is furnished with: an LED and a phosphor ZnSXSe1_X (0 < x < I) that contains at least one activating agent (activator) among Cu, Ag and Au and that, stimulated by rays irradiated from the LED, sends forth Iight.
This configuration provides for constructing a white-light emitting device whose temperature characteristics are stable and that utilizes a phosphor of high emission efficiency, which thus allows high-efficiency white-light emitting devices whose hue does not alter from long-term use to be achieved.
The abovementioned phosphox may be ZnS,YSe1_x (0_2 <_ x <_ 0.9), and may be rendered so that, stimulated by rays in a range of wavelengths 380 nm to nm irradiated from the LED, the phosphor sends forth light.
By combining a blue LED and a phosphor that produces fluorescence of 5 wavelength longer than that from the LED, this configuration enables a white-light emitting device of stabilized hue to be achieved.
The foregoing phosphor ZnSxSel X (0 < x < 1) further may contain at least one coactivator among Cl, Br, I, Al, In and Ga.
Utilizing the coactivator allows the light-emission efficiency to be heightened further.
The foregoing phosphor ZnSxSel X (0 < x < 1) may be in either a clumplike or powdered form.
Although phosphor usage methods that incorporate it as a powder into a synthetic polymer are well-known ways of employing the material, if it is in clump form, temperature elevation can be kept under control since heat generated within the phosphor is readily given off to the exterior.
A foregoing phosphor ZnSXSe~ X (0.5 < x S 0.9) may contain at least one of the activators Au and Cu, and be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from the LED, the phosphor sends forth light.
The configuration just noted, given that at least one of Au and Cu is employed for the activator, viewed in terms of efficiency enables the optimal combination of the two fluorescers that are components of the white-light emitting device to be achieved.
An aforementioned phosphor ZnS,YSe1 x (0.4 5 x 5 0.5) may contain the activator Ag and, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from the LED, sends forth light.
This configuration, viewed in terms of efficiency given that Ag is employed for the activator, enables an optimal combination constituting the white-light emitting device to be formed.
A white-light emitting device in another aspect of the invention may include, as the phosphor ZnSxSel X (0 < x < 1), at least one of a phosphor ZnSxSe1 X (0.7 <_ xS 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSei X (0.5 <_ x <_ 0.8) containing the activator Ag, and may be furnished with an LED that irradiates light in a range of wavelengths 410 nm to 490 nm, and a separate LED that irradiates red light.
According to this configuration, an RGB white-light emitting device can be constituted with the green (G) role being taken on by either of the phosphors just noted, and with a blue LED and a red LED. With red light therefore also being included, white light that for all applications is trouble-free can be made available.
A white-light emitting device in a further aspect of the present invention may include as the phosphor ZnSxSe1-X (0 < x < 1), at least one of a phosphor ZnSXSe1_X (0.7 < x< 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSe1 x (0.5 < x < 0.8) containing the activator Ag, and be additionally furnished with a separate phosphor that sends forth light of wavelength longer than that from the phosphor just noted, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors senf, forth light.
According to this configuration, with the green light (G) and red light (R) roles being taken on by phosphors of two kinds, and brought together with blue Light (B) from a blue LED, white light utilizable in all applications, including as a backlight for a liquid-crystal display, can be created.
A white-light emitting device in yet another aspect may include as the phosphor ZnSXSei-X (0 < x< 1), at least one of a phosphor ZnSXSe~_X (0.7 <_ x<_ 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnSxSe1 X
(0.5 < x _< 0.8) containing the activator Ag, and additionally be furnished with, as a separate phosphor, ZnSxSe1-x (0.2 <_ x_< 0.4) containing at least one of the activators Au and Cu, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors send forth light.
According to this configuration, the rel-light and green-Iight roles are taken on by ZnSSe phosphors and are brought together with blue light from a blue LED, wherein an RGB type of white-light emitting device applicable to any use whatever can be formed.
In an additional aspect of the present invention a white-light emitting device may be furnished with, as the phosphor ZnSxSe 1 x (0 < x < 1), a phosphor ZnSXSe1-X (0.2 < x_< 0.4) containing at Least one of the activators Au and Cu, and also be furnished with a separate phosphor that sends forth green light, and may be rendered so that, stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from an LED, both the phosphors send forth light.
This configuration brings together red-light whose role is taken on by the phosphor ZnSxSe 1 X (0.2 5 x <_ 0.4) and green Light that is allotted to another suitable phosphor with blue light from a blue LED to enable an RGB white-light emitting device to be formed.
The phosphor ZnSxSel X (0 < x< 1) may be in clumplike form, and may be mounted on, so as to mate surfaces with, either the blue LED or a heat-dissipating member furnished in the white-light emitting device.
With a clumplike phosphor, heat arising in the interior is readily transmitted to the phosphor surface'> mounting the phosphor as just mentioned on either a heat-dissipating member or the blue LED so that the mounting surfaces mate facilitates letting the heat escape.
An InGaN LED may be utilized for the foregoing blue LED. That makeup provides for a stable, low-cost blue LED, which contributes to achieving a highly reliable white-light emitting device.
It is preferable that the foregoing phosphors ZnSxSei X (0 < x < 1) be heat-treated in an atmosphere containing Zn vapor.
Through a technique of this sort phosphors of high fluorescing efficiency can be achieved.
A phosphor-manufacturing method of the present invention includes: a step of forming a phosphor ZnSxSe1 X (0 < x < 1) containing at least one among coactivators Cl, Br, I, Al, In and Ga~ and a step of carrying out a process, within a vaporous mixture of a vapor of at least one of activators Au, Cu and Ag and a vapor of Zn, of heating the coactivator-containing phosphor ZnSx,Se1_X (0 < x < 1) to the vaporous mixture temperature.
This method yields a phosphor ZnSXSe1-X (0 < x< 1) of high light-emission efficiency, containing activators and coactivators.
A white-light emitting device of the present invention, by utilizing fluorescing materials such as phosphors, makes it possible stably to produce, with good efficiency and without altering of hue relative to changes in temperature, white light of a color temperature of choice.
From the following detailed description in conjunction with the accompanying drawings, the foregoing and other objects, features, aspects and advantages of the present invention will become readily apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a chart showing that in embodying the present invention the temperature dependence of ZnSe phosphor is significant Fig. 2 is diagram illustrating basic thinking in the development of the phosphors ZnSxSel X in embodying the present invention Fig. 3 is a diagram showing fluorescence spectra for ZnSSe in which the activator Cu is utilized Fig. 4 is a diagram showing fluorescence spectra far ZnSSe in which the activator Ag is utilized Fig. 5 is a chromaticity diagram plotting the spectral peaks for ZnSSe in which the activator Cu is utilized and in which Ag is~
Fig. 6 is a chart showing the dependence of spectral peak on S atomic fraction, for ZnSSe in which the activator Cu is utilized and in which Ag is~
5 Fig. '7 is a chart illustrating the temperature dependence of the fluorescent intensity of ZnSSe in which the activator Cu is utilized Fig. 8 is a chart illustrating the temperature dependence of the fluorescent intensity of ZnSSe in which the activator Ag is utilized Fig. 9 is a view illustrating the configuration of a white-light emitting 10 device of Embodiment 1 of the present invention Fig. 10 is a view depicting the configuration of a white-light emitting device of Embodiment 2 of the present invention Fig. 11 is a view showing the configuration of a conventional white-light emitting device Fig. 12 is a view representing the configuration of another conventional white-light emitting device and Fig. 13 is a chromaticity diagram plotting color data for conventional white-light emitting devices.
DETAILED DESCRIPTION OF THE INVENTION
Next, using the drawings, an explanation of embodiments of the present invention will be made.
Basic Concept of the In vention In developing phosphors, crucial characteristics are the excitation-emission properties, and the emission efficiency. As far as the excitation-emission properties are concerned, in instances in which blue LEDs, which have seen significant advances in recent years, are employed as an optical excitation source the phosphors must be efficiently stimulated by blue light and exhibit fluorescence in yellow, which is blue's complementary color.
If white LEDs of the RGB type are to be manufactured, then it is necessary for the phosphors to express by blue light red and green fluorescence. The emission efficiency of a phosphor can be evaluated according to the dependence of its fluorescent intensity on temperature. In general, at low temperature phosphors have high emission efficiency, while their fluorescing efficiency drops with elevations in temperature. However, to what extent can the temperature be raised before the efficiency drops differs depending on the kind of phosphor.
Accordingly, if the fluorescence efficiency of a phosphor does not vary from low temperature to the temperature zone in which phosphors are employed, then its temperature characteristics are satisfactory and its emission efficiency is high.
If conventional phosphors are evaluated from these perspectives, then the fact that YAG types are limited to the yellow band means that their excitation-emission properties are inadequate. Zn~'e phosphors demonstrate emission that is convenient in terms of synthesizing white light of a color temperature of choice, but the wavelength of the excitation beam is restricted to 485 nm or thereabouts, and in that wavelength bandL the emission efficiency of an InGaN LED ends up being rather low. Consequently, the combination of wavelengths from YAG and ZnSe phosphors is not necessarily optimal.
Moreover, the temperature behavior of ZnSe phosphor was assayed, which indicated, as shown in Fig. I, that the temperature characteristics of ZnSe phosphor are not necessarily the best. At or around room temperature, ZnSe phosphor already exhibits remarkable temperature quenching, and not only is the efficiency not high, according as the LED temperature changes the proportions of blue and yellow light change, which ends up altering the hue (color temperature, etc.) of the white.
Under the circumstances, then, attention in the present invention was IO given to ZnS phosphors. ZnSe and ZnS are similar phosphors in which only the Se and S are interchanged. With ZnS, on account of its wider band gap than that of ZnSe, excitation light from violet to ultraviolet would be necessary in order to propose ZnS Iuminophors. Consequently, ZnS is not usable in white LEDs of the blue-light-excitation type. Nevertheless, ZnS phosphors have superlative temperature characteristics, and thus are widely used as phosphors for electron-beam excitation such as in television cathode-ray tubes. In light of these considerations, as represented in Fig. 2, the concept was hit upon that a phosphor possessing the combined superior features of ZnSe phosphors and ZnS
phosphors ought to be realizable with ZnS~Se1-X (0 < <~< 1), being a solid solution of ZnSe and ZnS.
It should be understood that while only "Z:nSe phosphors" and "ZnS
phosphors" have been referred to, in order for ZnSe and ZnS to operate as phosphors, it is necessary to disperse activators and coactivators into the paxent material (in this case ZnSe and ZnS). As activators for ZnS
luminophors, the Group Ib elements Ag, Cu and Au are known. Likewise, as coactivators, the Group VIIa elements F, Cl, Br and I, as well as the Group IIIa elements Al, In and Ga are known. As far as coactivators are concerned, the phosphor emission behavior does not change much no matter what element is used.
As far as activators are concerned, it is known that the fluorescent wavelength shortens when Ag is used, and lengthens when Cu or Au is used.
There is no major difference between Cu and Au. Given these considerations, activators and coactivators were introduced into ZnSXSe~ X of a variety of S
atomic fractions (x) to prepare phosphors, and their excitation-emission properties and temperature characteristics were investigated to find out whether they could be exploited in fabricating white LEDs.
Phosphor ,Selection ZnSSe into which iodine was incorporated by the iodine transport method was composed. ZnSSe phosphors were prepared by diffusing Cu or Ag into the ZnSSe within a Zn atmosphere. The results are set forth in the following.
Emission spectra for ZnS,riSe r_x (x = 0, 0.25, 0.4, 0.6, 0.8) into which Cu and I were introduced, and emission spectra for ZnS,YSex x (x = 0, 0_4, 0.6, 0.8) into which Ag and I were introduced are shown respectively in Fig. 3 and Fig.
4.
For the measurements, a beam from a He-Cd laser of 325 nm wavelength was employed as the excitation light. In either instance, with increasing S atomic fraction x the fluorescent wavelength is shortened. As to the activators, it is evident from the spectra that with the ZnSSe phosphors in which Ag was employed, the fluorescent wavelength is shorter than with those in which Cu was employed.
Chromaticities were calculated from the spectra in Figs. 3 and 4 and plotted on the Fig. 5 chromaticity diagram. As will be understood from Fig. 5, these chromaticity coordinates form the complementary colors for violet to blue-green, 380 to 500 nm~ thexefore, blending these phosphor fluorescences with light of 380 to 500 nm can yield white. The problem remaining was whether the ZnSSe phosphor can be stimulated by the abovementioned visible light. Thus, an excitation spectrum for ZnSSe (change in fluorescent intensity as the excitation wavelength is varied) was measured to find the excitation peak. Therein, a ZnSSe phosphor of 1 mm thickness was used in the measurement.
In Fig. 6 the peak wavelengths in the excitation spectrum for ZnSxSer x (x = 0, 0.25, 0.4, 0_6, 0.8) into which Cu and I were introduced, and the peak wavelengths in the excitation spectrum for ZnS~Sea X (x = 0, 0.4, 0.6, 0.8) into which Ag and I were introduced are shown. In either case, when the S atomic fraction is enlarged the peak in the excitation spectrum is shortened in wavelength. Although a measurement was not made on a phosphor in which the S atomic fraction is 1-that is, on ZnS--extrapolating from the data in Fig. 6, it may be inferred that up until the S atomic fraction is about 0.9, the phosphor may be stimulated with visible rather than ultraviolet light.
Next the dependence of fluorescent intensity on temperature was measured. The results are arranged together in Figs. 7 and 8. It is evident from Figs. 7 and 8 that rendering the S atomic fraction x about 0.2 or more dramatically improves the temperature characteristics by comparison to the case in which the S atomic fraction is zero (ZnSe).
5 Illuminating the phosphor with excitation rays of the foregoing violet to blue-green of 380 to 500 nm, and mixing together the fluorescence and the excitation rays allows white and the intermediate colors surrounding it (pink, pale green, bluish white, etc.) to be synthesized. In order to produce the white that is industrially most important, however, the combination of excitation rays 10 and phosphor can be narrowed down a little more.
s1-First, the instances in which Cu and Au were employed as activators are examined. In these cases, if the S atomic fraction x were low, the temperature characteristics would suffer, and further, longer-wavelength excitation rays would be necessary. With InGaN LEDs, because the efficiency 15 with which they excite proves to be highest at wavelengths in the vicinity of 400 to 4v0 nm, they are undesirable to use for longer-wavelength excitation light.
Using ZnS~Se1 X (0.5 <_ x <_ 0.9) for the phosphor and using an LED whose emission spectrum spans wavelengths of 410 to 490 nm for the excitation rays is preferable.
s2 - Next, the instance in which Ag was employed is considered in the same way, wherein using ZnS~Se1_X (0.4 _< x< 0.5) for the phosphor and using an LED whose emission spectrum spans wavelengths of 410 to 460 nm for the excitation rays is preferable.
The foregoing phosphors may also be employed as the green phosphor and red phosphor for a white LED of the RGB type.
G- In cases in which Au or Cu are employed as activators, ZnSx,Se1 ~ (0.7 S x <_ 0.9) may be utilized for the green phosphor. Likewise, in cases employing Ag as an activator, ZnSxSes-x (0.5 < x <_ 0.8) may be utilized. In composing an RGB type of white, ZnSSe phosphors may be used for both the red phosphor and the green phosphor, or for one or the other a different phosphor may equally well be used.
R - In turn, as far as red light is concerned, since high-efficiency red LEDs are available, a red LED may be employed instead of a red phosphor. A
problem in that case, however, is that since the deterioration rates of blue LEDs and red LEDs are different, the hue of the white will end up varying over time.
All told, it would seem that combining slow-to-deteriorate phosphors would be advantageous over blue LEDs as an optical excitation source.
It should be noted that although the activators were dispersed into the foregoing phosphors within a Zn atmosphere, they may equally well be dispersed within for example an Se atmosphere. Nevertheless, empirically there is a likelihood that the fluorescing efficiency of phosphors into which activators have been dispersed within an Se atmosphere will turn out low.
Features of ZnSSe phosphors include, to name examples, the fact that the source materials are modestly priced and that clumplike rather than powdered phosphors can easily be synthesized. Routinely, phosphors have been rendered into powder form, and have been spread onto a glass substrate or have been dispersed into a.synthetic polymer. With ZnSSe phosphors, nevertheless, the phosphors can be employed in clump form without making them into a powder, eliminating cost problems. While that is an advantage to using clumplike phosphors, compared with the situation in which a phosphor is dispersed into a synthetic polymer, with a clumplike phosphor, because heat generated inside the phosphor is readily dissipated to the exterior, the phosphor temperature is not liable to rise. Consequently, the lifespan of the white LEDs is prolonged as a result, enabling high-output-power white LEDs to be realized.
White Light EmittingDevice Configuration Reference is now made to Fig. 9, a view illustrating the configuration of a white-light emitting device in Embodiment 1 of the present invention. A blue LED I is attached to a mounting portion 9 of a lead frame so that their like surfaces are matched. Through wires 5 out of external electrodes 7a, '7b, electric current is conducted into (not-illustrated) chip electrodes on the blue LED 1.
A
heat-dissipating member 11 made of aluminum is disposed encompassing the blue LED. A transparent polymer 6 into which a~ diffusant is dispersed is disposed covering the blue LED, and a phosphor plate 3 is arranged atop the transparent polymer 6.
The phosphor 3 is established from ZnSxSe1 X of S atomic fraction x, and an activator, and is adjusted so as to lead to white light of a predetermined color temperature. Adjusting the composition of and the activator in the phosphor ZnSRSe1 ~ to attain white light of a predetermined color temperature is an important element of the present invention. Furthermore, what with the specific weights for adjustment being small and the breadth of the adjustment being limited, in some cases the emission spectrum of the blue LED is also an object of adjustment.
The blue LED into which current has been fed through the external electrodes 7a, 7b emits Light of a blue color, shining the light onto the phosphor 3. The light irradiated from the blue LED 1 is shone onto the phosphor plate 3, and this fluorescent emission material is stimulated to give off fluorescence.
Though the rays irradiated from the blue LED 3 illuminate the phosphor plate 3, this does not mean that all are utilized in excitation some pass through the phosphor plate 3 without contributing to excitation. Consequently, fluorescence of a predetermined wavelength and blue light emitted from the blue LED are combined to create white light of a predetermined color temperature.
Reference is made to Fig. 10, a view representing a white-light emitting device in Embodiment 2 of the present invention. What is different from the I5 white-Iight emitting device represented in Fig. 9 is that two phosphors are Laid out-a first phosphor 3 and a second phosphor 13. The first phosphor 3 is a green phosphor, and is formed for example by a ZnSSe plate (ZnS atomic fraction 0.6). Likewise, the second phosphor I3 is a red phosphor, and is formed for example by ZnSSe crystal (ZnS atomic fraction: 0.25). An RGB-type of white-light emitting device can be configured by the blue LED 1, and the foregoing red phosphor 13 and green phosphor 3.
Embodiments Embodiment 1 The white-light emitting device depicted in Fig. 9 was prepared. At first a ZnSSe crystal was grown using the iodine transport method and subsequently underwent heat treatment within a 1000°C atmosphere in which Zn and Cu vapors were mixed, whereby a ZnSo.sSeo.4 crystal of predetermined composition (ZnS atomic fraction 0.6) was prepared. This phosphor corresponds to the rhombic mark for ZnS atomic fraction 0.6 nearby wavelength 570 nm on the chromaticity diagram; and is a yellow-light emitting phosphor. A ZnSSe plate of 250 microns thickness was cut out from the ZnSo.sSeo.4 crystal. Both sides of the ZnSSe plate were polished to a mirror-like finish, bringing the thickness down to 200 urn, and the polished plate was sliced into a 3 mm square to produce a ZnSo.sSeo.4 phosphor plate.
In addition, a blue LED chip of 450 nm emission wavelength, having an InGaN active layer, was readied. An Ag paste was employed to bond the LED
chip onto a chip die (lead-frame mounting portion) 9, as shown in Fig. 9, made of Al. Furthermore, the LED-chip electrodes and the chip-die electrodes were wire-bonded with Au wire. Thereafter, by covering the LED with a transparent synthetic polymer 6, and installing the ZnSSe phosphor plate 3 above the LED, a white-light emitting device was fabricated. Current was passed into the white-light emitting device to cause it to emit light, giving rise to blue light issuing from the LED and yellow fluorescence sent forth by excitation via the blue light, whereby emission of white light of 5000 K color temperature could be produced.
Embodiment 2 The white-light emitting device depicted in Fig. 10 was prepared. A
ZnSSe plate of 250 microns thickness was cut out from a ZnSo.sSeo.4 crystal (ZnS
atomic fraction 0.6) at first being grown using the iodine transport method, and subsequently undergoing heat treatment within a 1000°C atmosphere in which 5 Zn and Ag vapors were mixed. This phosphor corresponds to the black-dot mark for ZnS atomic fraction 0.6 on the chromaticity diagram, and is a green-light emitting phosphor. Both sides of the ZnSSe plate were polished to a mirror-like finish, bringing the thickness down to 200 microns, and the polished plate was sliced into a 3 mm square to produce a ZnSSe phosphor plate (green phosphor:
10 first phosphor).
In addition, a 400-micron square, 250-naicron thick ZnSo.2sSeo.~S
phosphor plate (red phosphor: second phosphor) was prepared from a ZnSo.2sSeo.~S crystal (ZnS atomic fraction 0.25) that was grown using the iodine transport method and subsequently underwent heat treatment within a 1000°C
15 atmosphere in which Zn and Cu vapors were mixed. This phosphor corresponds to the rhombic mark for ZnS atomic fraction 0.25 on the chromaticity diagram and is a red-light emitting phosphor.
In addition, a blue LED chip of 450 nm emission wavelength, having an InGaN active layer, was readied. An Ag paste was employed to bond the LED
20 chip onto the chip die (mounting portion of a lead frame) 9, as shown in Fig. 10, made of Al, and further the LED-chip electrodes and the chip-die electrodes were wire-bonded with Au wire. In addition, the second phosphor was also bonded to the chip die.
Thereafter, by covering the LED with a transparent synthetic polymer 6 into which a diffusant was dispersed, and then inst;~lling the ZnSSe phosphor plate as the first phosphor 3 above the LED, an RGB type of white-light emitting device was fabricated. By passing current into the white-light emitting device to cause it to emit light, emission of white light of 5000 K color temperature could be produced.
A white-light emitting device of the present invention, by utilizing fluorescing materials such as phosphors, makes it possible stably to produce, with good efficiency and without altering of hue relative to changes in temperature, white light of a color temperature of choice, and therefore is expected to find wide-ranging uses in commercial applications and industrial applications in which great importance is attached to hue.
Only selected embodiments have been chosen to illustrate the present invention. To those skilled in the art, however, it will be apparent from the foregoing disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing description of the embodiments according to the present invention is provided for illustration only, and not for limiting the invention as defined by the appended claims and their equivalents.
Claims (16)
1. A white-light emitting device furnished with an LED (light-emitting diode) and a phosphor ZnS x Se1-x (0 < x < 1) that contains at least one activator among Cu, Ag and Au, and that sends forth light when stimulated by rays irradiated from said LED.
2. A white-light emitting device as set forth in claim 1, wherein said phosphor is ZnS x Se1-x (0.2 <= x <= 0.9), and sends forth light when stimulated by rays in a range of wavelengths 380 nm to 500 nm irradiated from said LED.
3. A white-light emitting device as set forth in claim 1 or 2, wherein said phosphor ZnS x Se1-x(0 < x < 1) further contains at least one coactivator among Cl, Br, I, Al, In and Ga.
4. A white-light emitting device as set forth in any of claims 1 through 3, wherein said phosphor ZnS x Se1-x (0 < x < 1) is in either a clumplike or powdered form.
5. A white-light emitting device as set forth in any of claims 1 through 4, wherein said phosphor is ZnS x Se1-x (0.5 <= x <= 0.9), contains at least one of the activators Au and Cu, and sends forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
6. A white-light emitting device as set forth in any of claims 1 through 4, wherein said phosphor is ZnS x Se1-x (0.4 <= x <= 0.5), contains the activator Ag, and sends forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
7. A white-light emitting device as set forth in any of claims 1 through 4, including, as said phosphor ZnS x Se1-x (0 < x < 1), at least one of a phosphor ZnS x Se 1-x (0.7 <= x <= 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnS x Se 1-x (0.5 <= x <= 0.8) containing the activator Ag; and further furnished with said LED irradiating rays in a range of wavelengths 410 nm to 490 nm, and a separate LED that irradiates red light.
8. A white-light emitting device as set forth in any of claims 1 through 4, including, as said phosphor ZnS x Se 1-x (0 < x < 1), at least one of a phosphor ZnS x Se1-x (0.7 <= x <= 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnS x Se 1-x (0.5 <= x <= 0.8) containing the activator Ag; and further furnished with a separate phosphor that sends forth light of wavelength longer than that from said phosphor; wherein both said phosphors send forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
9. A white-light emitting device as set forth in any of claims 1 through 4, including, as said phosphor ZnS x Se 1-x (0 < x < 1), at least one of a phosphor ZnS x Se 1-x (0.7 <= x <= 0.9) containing at least one of the activators Au and Cu, and a phosphor ZnS x Se 1-x (0.5 <= x <= 0.8) containing the activator Ag; and further furnished with, as a separate phosphor, ZnS x Se 1-x (0.2 <= x <=
0.4) containing at least one of the activators Au and Cu; wherein both said phosphors send forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
0.4) containing at least one of the activators Au and Cu; wherein both said phosphors send forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
10. A white-light emitting device as set forth in any of claims 1 through 4, furnished with, as said phosphor ZnS x Se 1-x (0 < x < 1), a phosphor ZnS x Se 1-x (0.2 <= x <= 0.4) containing at least one of the activators Au and Cu;
and further furnished with a separate phosphor that sends forth green light; wherein both said phosphors send forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
and further furnished with a separate phosphor that sends forth green light; wherein both said phosphors send forth light when stimulated by rays in a range of wavelengths 410 nm to 490 nm irradiated from said LED.
11. A white-light emitting device as set forth in any of claims 1 through 10, wherein said phosphor ZnS x Se1-x (0 < x < 1) is in clumplike form and is mounted on, so as to mate surfaces with, either said LED or a heat-dissipating member furnished in the white-light emitting device.
12. A white-light emitting device as set forth in any of claims 1 through 11, wherein an InGaN LED is utilized for said LED.
13. A white-light emitting device as set forth in any of claims 1 through 12, wherein said phosphor ZnS x Se1-x (0 < x < 1) is heat-treated in an atmosphere containing Zn vapor.
14. A phosphor-manufacturing method including: a step of forming a phosphor ZnS x Se1-x (0 < x < 1) containing at least one among coactivators Cl, Br, I, Al, In and Ga; and a step of carrying out a process, within a vaporous mixture of a vapor of at least one of activators Au, Cu and Ag and a vapor of Zn, of heating said coactivator-containing phosphor ZnS x Se1-x (0 < x < 1) to the vaporous mixture temperature.
15. A phosphor manufactured by the phosphor-manufacturing method set forth in claim 14.
16. A white-light emitting device including a phosphor manufactured by the phosphor-manufacturing method set forth in claim 14.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003-303210 | 2003-08-27 | ||
| JP2003303210A JP2005072479A (en) | 2003-08-27 | 2003-08-27 | White light emitting device, phosphor, and its manufacturing method |
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| CA2475289A1 true CA2475289A1 (en) | 2005-02-27 |
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| CA002475289A Abandoned CA2475289A1 (en) | 2003-08-27 | 2004-07-16 | White-light emitting device, and phosphor and method of its manufacture |
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| US (2) | US20050046334A1 (en) |
| EP (1) | EP1511089A2 (en) |
| JP (1) | JP2005072479A (en) |
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| CN (1) | CN1591919A (en) |
| CA (1) | CA2475289A1 (en) |
| TW (1) | TW200509419A (en) |
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| DE102004053594A1 (en) * | 2004-01-21 | 2005-08-18 | Agilent Technologies, Inc. (n.d.Ges.d.Staates Delaware), Palo Alto | Apparatus and method for emitting output light using a group IIB element selenide-based phosphor material |
| TWI413274B (en) | 2005-03-18 | 2013-10-21 | Mitsubishi Chem Corp | Light-emitting device, white light-emitting device, lighting device and image display device |
| KR101142519B1 (en) * | 2005-03-31 | 2012-05-08 | 서울반도체 주식회사 | Backlight panel employing white light emitting diode having red phosphor and green phosphor |
| ATE546836T1 (en) * | 2005-04-21 | 2012-03-15 | Fiat Ricerche | USE OF A TRANSPARENT LED DISPLAY DEVICE IN A MOTOR VEHICLE |
| WO2006126817A1 (en) * | 2005-05-24 | 2006-11-30 | Seoul Semiconductor Co., Ltd. | Green phosphor of thiogallate, red phosphor of alkaline earth sulfide and white light emitting device thereof |
| CN100365837C (en) * | 2005-06-13 | 2008-01-30 | 北京有色金属研究总院 | Illuminating device and its mfg. method |
| KR100601200B1 (en) * | 2005-06-17 | 2006-07-13 | 서울반도체 주식회사 | Red fluorescent substance and light-emitting diode using the same |
| US20070007542A1 (en) * | 2005-07-07 | 2007-01-11 | Sumitomo Electric Industries,Ltd. | White-Light Emitting Device |
| KR100724591B1 (en) * | 2005-09-30 | 2007-06-04 | 서울반도체 주식회사 | Light emitting device and LCD backlight using the same |
| KR100735453B1 (en) | 2006-02-22 | 2007-07-04 | 삼성전기주식회사 | White light emitting device |
| US8323529B2 (en) * | 2006-03-16 | 2012-12-04 | Seoul Semiconductor Co., Ltd. | Fluorescent material and light emitting diode using the same |
| TWI455891B (en) * | 2008-02-06 | 2014-10-11 | Univ Kumamoto Nat Univ Corp | A method of producing group ii-vi compound semiconductor, a method of producing group ii-vi compound semiconductor fluorescent substance, and group ii-vi compound semiconductor with hexagonal crystal structure |
| TW200949896A (en) * | 2008-05-27 | 2009-12-01 | Tatung Co | A device with electron beam excitation for making white light source |
| JP2009289961A (en) * | 2008-05-29 | 2009-12-10 | Wade Lee Wang | Production method of white light by purple led |
| JP2010092705A (en) | 2008-10-08 | 2010-04-22 | Sony Corp | Illuminating device and display device using this |
| US9082349B2 (en) * | 2011-08-30 | 2015-07-14 | Sharp Laboratories Of America, Inc. | Multi-primary display with active backlight |
| US10125971B2 (en) * | 2013-02-19 | 2018-11-13 | Michael Graziano | LED lamp integrated to electric fan |
| JP7561481B2 (en) * | 2018-02-05 | 2024-10-04 | 日本電気硝子株式会社 | Manufacturing method for individual pieces of phosphor glass thin plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US2623858A (en) * | 1949-01-14 | 1952-12-30 | Hartford Nat Bank & Trust Co | Zinc sulfide phosphors containing aluminum |
| US2948635A (en) * | 1959-01-12 | 1960-08-09 | Gen Electric | Phosphor evaporation method and apparatus |
| JP3940596B2 (en) * | 2001-05-24 | 2007-07-04 | 松下電器産業株式会社 | Illumination light source |
| US6987353B2 (en) * | 2003-08-02 | 2006-01-17 | Phosphortech Corporation | Light emitting device having sulfoselenide fluorescent phosphor |
| US7488990B2 (en) * | 2004-04-02 | 2009-02-10 | Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. | Using multiple types of phosphor in combination with a light emitting device |
| US20060006397A1 (en) * | 2004-07-09 | 2006-01-12 | Chua Janet B Y | Device and method for emitting output light using group IIA/IIB selenide sulfur-based phosphor material |
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2003
- 2003-08-27 JP JP2003303210A patent/JP2005072479A/en active Pending
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2004
- 2004-07-16 CA CA002475289A patent/CA2475289A1/en not_active Abandoned
- 2004-07-20 TW TW093121659A patent/TW200509419A/en unknown
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- 2004-08-20 US US10/711,063 patent/US20050046334A1/en not_active Abandoned
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| TW200509419A (en) | 2005-03-01 |
| EP1511089A2 (en) | 2005-03-02 |
| KR20050022361A (en) | 2005-03-07 |
| CN1591919A (en) | 2005-03-09 |
| US20070194282A1 (en) | 2007-08-23 |
| JP2005072479A (en) | 2005-03-17 |
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